Lecture 8 Hybrid Rocket Propulsion Fundamentals - Space ...

AA 284a Advanced Rocket Propulsion

Lecture 8 Hybrid Rocket Propulsion Fundamentals Prepared by Arif Karabeyoglu Department of Aeronautics and Astronautics Stanford University May 07, 2012

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AA 284a Advanced Rocket Propulsion Hybrid Rocket Configuration Fuel and oxidizer are physically separated One of the two is in solid phase

Most Hybrids:

Reverse Hybrids:

Oxidizer: Liquid Fuel: Solid

Oxidizer: Solid Fuel: Liquid

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AA 284a Advanced Rocket Propulsion Hybrid Rocket Configuration-AMROC Booster




AMROC H-1800 (Test motor DM-01): 250 klb thrust Stanford University 3

Karabeyoglu

AA 284a Advanced Rocket Propulsion Hybrid Rocket System Solid Fuel • Polymers: Thermoplastics, (Polyethylene, Plexiglas), Rubbers (HTPB) • Wood, Trash, Wax

Liquid Oxidizer • Cryogenic: LO2 • Storable: H2O2, N2O, N2O4, IRFNA

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AA 284a Advanced Rocket Propulsion Hybrid Combustion Scheme

Concentration Profiles

Temperature Profile

Velocity Profile

Yo = 1

Te

Ue

Tb

Oxidizer + Products

Flame Zone

Ts

Fuel + Products

Fuel Grain z

•

x

Ta

Diffusion limited combustion – Burning Rate Law: independent of pressure (flux dependent)

•

Flame zone away from surface and blocking effect – Low regression rate Stanford University 5

n r& = a Gox

AA 284a Advanced Rocket Propulsion Comparison of Hybrid and Solid Rocket Combustion Schemes

Solid

Hybrid

• Active grain • Premixed flame (globally). • Heteregeneous rxns. • Pressure dependent burning rate. • High burning rates (high thrust density).

• • • •

Inert grain Diffusion flame in a TBL. No heteregeneous rxns. Mass flux dependent burning rate. • Low burning rates (low thrust density).

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Karabeyoglu

AA 284a Advanced Rocket Propulsion Advantages of Hybrids Compared to

Solids

Liquids

Simplicity

- Chemically simpler - Tolerant to processing errors

- Mechanically simpler - Tolerant to fabrication errors

Safety

- Reduced chemical explosion hazard - Thrust termination and abort possibility

- Reduced fire hazard - Less prone to hard starts

Performance Related

- Better Isp performance - Throttling/restart capability

- Higher fuel density - Easy inclusion of solid performance additives (Al, Be)

Other

- Reduced environmental impact

- Reduced number and mass of liquids

Cost

- Reduced development costs are expected - Reduced recurring costs are expected

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Karabeyoglu

AA 284a Advanced Rocket Propulsion Hybrid Rocket History Early History (1932-1960) • 1932-1933: GIRD-9 (Soviet) – LO2/Gellified gasoline 60 lbf thrust motor – Firsts • Hybrid rocket • Soviet rocket using a liquid propellant • First fast burning liquefying fuel – Tikhonravov and Korolev are designers – Maximum altitude: 1,500 m

• 1937: Coal/Gaseous N2O hybrid motor 2,500 lbf thrust (Germany) • 1938-1939: LOX/Graphite by H. Oberth (Germany) • 1938-1941: Coal/GOX by California Rocket Society (US). • 1947: Douglas Fir/LOX by Pacific Rocket Society (US) • 1951-1956: GE initiated the investigations in hybrids. H2O2/Polyethylene. (US)

GIRD-9

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Karabeyoglu

AA 284a Advanced Rocket Propulsion Hybrid Rocket History •

•

Era of Enlightenment (1960-1980) 1960's: Extensive research at various companies. – Chemical Systems Division of UTC • Modeling (Altman, Marxman, Ordahl, Wooldridge, Muzzy etc…) • Motor testing (up to 40,000 lb thrust level) – LPC: Lockheed Propulsion Company, SRI: Stanford Research Institute, ONERA (France) 1964-1984: Flight System Development – Target drone programs by Chemical Systems Division of UTC • Sandpiper, HAST, Firebolt – LEX Sounding Rocket (ONERA, France) – FLGMOTOR Sounding Rocket (Sweeden)

CSD’s Li/LiH/PBAN-F2/O2 Hybrid Measured Isp=400 sec

Firebolt Target Drone

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Karabeyoglu

AA 284a Advanced Rocket Propulsion Hybrid History Recent History (1981-Present) • •

•

• •

1981-1985: Starstruck company developed and sea launched the Dolphin sounding rocket (35 klb thrust) 1985-1995: AMROC continuation of Starstruck – Tested 10, 33, 75 klb thrust subscale motors. – Developed and tested the H-1800, a 250 klb LO2/HTPB motor. 1990’s: Hybrid Propulsion Development Program (HPDP) – Successfully launched a small sounding rocket. – Developed and tested 250 klb thrust LO2/HTPB motors. 2002: Lockheed developed and flight tested a 24 inch LO2/HTPB hybrid sounding rocket (HYSR). (60 klb thrust) 2003: Scaled Composites and SpaceDev have developed a N2O/HTPB hybrid for the sub-orbital vehicle SpaceShipOne. (20 klb thrust)

Dolphin

AMROC Motor Test

SpaceShipOne

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Karabeyoglu

AA 284a Advanced Rocket Propulsion Hybrid Combustion Theory (Diffusion Limited Model) • Developed by G. Marxman in early 1960’s. • The purpose is to predict the regression rate. • Assumptions: – Steady-state operation. – Simple grain configuration (flat plate). – No exothermic reactions in the solid grain (No oxidizer in solid phase). – Oxidizer enters the port as a uniform gas. – Le=Pr=1 (Le = κ D ) – No heat transfer to the ambient air through the walls of the rocket. – All kinetic effects are neglected (Characteristic times for all chemical rxns Multi-port design Issues with multi-port design • Excessive unburned mass fraction (i.e. typically in the 5% to 10% range). •

Complex design/fabrication, requirement for a web support structure.

•

Compromised grain structural integrity, especially towards the end of the burn.

•

Uneven burning of individual ports.

•

Requirement for a substantial precombustion chamber or individual injectors for each port.

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AA 284a Advanced Rocket Propulsion Disadvantage of Multiport Designs Lockheed Martin (2006) 43 ports

CSD (1967) 13 ports

AMROC (1994) 15 ports Stanford University 19

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AA 284a Advanced Rocket Propulsion Approaches for High Regression Rate Technique

Add oxidizing agents selfdecomposing materials Add metal particles (micron-sized)

Add metal particles (nano-sized) Use Swirl Injection

Fundamental Principle

Shortcoming

Increase heat • Reduced safety transfer by • Pressure introducing surface dependency reactions Increased radiative • Limited heat transfer improvement • Pressure dependency Increased radiative • High cost heat transfer • Tricky processing Increased local mass flux

• Increased complexity • Scaling?

All based on increasing heat transfer to fuel surface Stanford University 20

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AA 284a Advanced Rocket Propulsion Entrainment Mass Transfer Mechanism

ρe u e Reacting Droplets

Diffusion Flame Roll Waves

Liquid Layer

Fuel Grain

Regression Rate = Entrainment + Vaporization Stanford University 21

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